Three-dimensional structure and method for production thereof

ABSTRACT

It is intended to provide an optical three-dimensional object as will be described below which has a high impact resistance and is superior in dimensional accuracy, mechanical properties such as tensile strength, and other properties such as water resistance, moisture resistance and heat resistance, and a method of producing the same. An optical three-dimensional object includes multiple cured resin layers containing at least cured resin layer that has a sea-island microstructure in which fine island components of a polymer differing from a cured resin constituting the sea component and have a particle diameter of 20 to 2,000 nm are dispersed in the sea component made of the cured polymer; and a method of producing this optical three-dimensional object by stereolithographic molding method with the use of a photo curable resin composition containing a homogeneous mixture of a curable resin component for forming the sea component with a component (preferably a polyalkylene ether compound) for forming the polymeric island components.

TECHNICAL FIELD

This invention relates to a three-dimensional object formed by using anactinic radiation-curable resin composition and a method of producingthe same. More specifically, it relates to a three-dimensional objectwhich is produced by a fabricating procedure of accumulating cured resinlayers layer by layer upon irradiation with an actinic radiation such aslight and has a unique microstructure that cannot be found in thebackground art, and a method of producing the same. Owing to thespecific microstructure, the three-dimensional object according to thepresent invention is superior particularly in mechanical properties suchas impact resistance.

BACKGROUND ART

In recent years, there has been widely employed the opticalstereolithographic molding method of a liquid photo curable resincomposition based on data put in three-dimensional CAD, since thismethod makes it possible to obtain a desired three-dimensionalfabricated object at a high dimensional accuracy without preparing a dieor the like (see, for example, Patent Documents 1 to 6).

A typical example of optical stereolithographic molding techniques(hereinafter optical stereolithographic molding will be sometimes called“stereolithography”) is a method comprising selectively irradiating theliquid surface of a liquid photo curable resin in a container with anultraviolet laser under computer control so as to give a desiredpattern, curing the resin selectively at a thickness, providing a liquidresin for a single layer on the thus cured layer, curing it byirradiating with an ultraviolet laser in the same manner, and repeatingthe buildup procedure for obtaining cured layers to thereby give athree-dimensionally object. This stereolithography is widely employedtoday, since an object in considerably complicated shape can be easilyproduced thereby within a relatively short period of time.

Resins or resin compositions to be used in the stereolithography shouldhave various characteristics, for example, having a high curesensitivity upon irradiation with an actinic radiation, a fabricatedobject having a favorable resolution and a high fabricating accuracy,having a low volume shrinkage after curing, a cured object havingexcellent mechanical properties, having a favorable self-adhesiveness,having favorable curing properties under oxygen atmosphere, having a lowviscosity, being excellent in water resistance and moisture resistance,absorbing little water or moisture with the passage of time, beingexcellent in dimensional stability and so on.

As photo curable resin compositions for stereolithography, various photocurable resin compositions such as photo curable resin compositionscontaining a radical-polymerizable organic compound; photo curable resincompositions containing a cationic-polymerizable organic compound; andphoto curable resin compositions containing both of aradical-polymerizable organic compound and a cationic-polymerizableorganic compound have been proposed and used. Examples of theradical-polymerizable organic compound to be used in these cases include(meth)acrylate compounds, urethane (meth)acrylate compounds, polyester(meth)acrylate compounds, polyether (meth)acrylate compounds, epoxy(meth)acrylate compounds and so on, while examples of thecationic-polymerizable organic compound include various epoxy compounds,cyclic acetal compounds, thiirane compounds, vinyl ether compounds,lactones and so on.

It has been a practice to control various properties such as thefabricating speed and the fabricating accuracy in the stereolithography,and dimensional accuracy, mechanical properties, water resistance andmoisture resistance of the object obtained by stereolithography, byappropriately selecting a polymerizable component constituting a photocurable resin composition or combining two or more specificpolymerizable components.

For example, it is known that an object by stereolithography having ahigh dimensional stability can be obtained by using a photo curableresin composition containing a cationic-polymerizable epoxy compound. Ina photo curable resin composition containing epoxy compounds, moreover,it is proposed to use a photo curable resin composition which contains acationic-polymerizable organic compound such as an epoxy compoundtogether with a radical-polymerizable organic compound such as a(meth)acrylate compound so as to relieve a lowering in the fabricatingspeed caused by the epoxy compound having a low reaction speed (see, forexample, Patent Document 7).

Although objects by stereolithography, which are obtained by theexisting techniques, are excellent in fabricating accuracy, dimensionalaccuracy, heat resistance, tensile strength, water resistance, chemicalresistance and so on, they are still insufficient in impact resistance,etc. For example, although the above-described object obtained by usinga photo curable resin composition containing a cationic-polymerizableorganic compound such as an epoxy compound together with aradical-polymerizable organic compound such as a (meth)acrylate compoundis excellent in dimensional stability and so on, it is easily destroyedbecause of having an insufficient impact resistance.

With the diffusion of the stereolithographic techniques, there have beenproduced fabricated objects having complicated shapes or structures. Forexample, various fabricated objects having thin parts and small-sizedparts are produced. When a fabricated object has a poor impactresistance in such a case, the object frequently suffers from breakageat a thin part or a small-sized part in the course of the production orutilization thereof. In recent years, moreover, fabricated objects areproduced not only as mere models (dummies) but also as products forpractical use such as matrices, processing members and machine parts. Inthese cases, it is required that the fabricated object are excellent inimpact resistance as well as tensile strength. However, objects bystereolithography in the background art are still unsatisfactory fromthe viewpoint of impact resistance.

There has been known a photo curable resin composition comprisingorganic polymer solid particles and/or inorganic solid particles havinga particle diameter of from 3 to 70 μm (see Patent Document 8). Anobject by stereolithography, which is produced by using the photocurable resin composition described in this Patent Document 8, has aphase state wherein the organic polymer solid particles and/or inorganicsolid particles having a particle diameter of 3 to 70 μm are dispersedin the photo cured resin. Since the organic polymer solid particlesand/or inorganic solid particles having a particle diameter of 3 to 70μm are dispersed in the photo cured resin phase, this object has a lowvolume shrinkage and a high dimensional stability. Moreover, it hasfavorable properties, for example, excellent mechanical properties suchas tensile strength and flexural strength, compared with athree-dimensional molded object without the above-described solidparticles. As the results of examinations by the present inventors,however, it is clarified that the object by stereolithography has aninsufficient toughness (or durability) in the photo cured resin phaseand there is still room for improvement in the impact resistancethereof.

Furthermore, attempts have been made to add a specific polyether havinghydroxyl groups at both ends to a resin composition forstereolithography containing a cationic-polymerizable compound havingepoxy group and an a radiation-sensitive cationic-polymerizationinitiator to thereby prevent curing failure of the composition caused byoxygen, decrease shrinkage upon curing and improve the dimensionalstability, load deflection and tensile elongation thereof (see PatentDocument 9). As the results of investigations by the present inventors,however, it is clarified that a high load deflection and a favorabletensile elongation are hardly compatible in an object bystereolithography, which is obtained from the resin composition forstereolithography as reported by this Patent Document 9 and, moreover,the object has an insufficient impact resistance.

(Patent Document 1) JP-A-56-144478

(Patent Document 2) JP-A-60-247515

(Patent Document 3) JP-A-62-35966

(Patent Document 4) JP-A-2-113925

(Patent Document 5) JP-A-2-153722

(Patent Document 6) JP-A-3-41126

(Patent Document 7) JP-B-7-103218

(Patent Document 8) JP-A-7-26060

(Patent Document 9) JP-A-2003-73457

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a three-dimensionalobject (an object by stereolithography) which is superior in dimensionalstability, mechanical properties such as tensile strength, andappearance and so on and, particularly superior in impact resistance anda method of producing the same.

To overcome the above problem, the present inventors conducted intensivestudies. In the course of the studies, they researched and investigatedmicrostructures of cured resins constituting an object bystereolithography, which is obtained by photo curable resincompositions, and therefore found that the microstructures in the curedresin parts closely relate to the physical properties such as impactresistance of the object. As the results of subsequent studies, thepresent inventors have successfully produced a unique object bystereolithography, including a plurality of photo cured resin layerseach having a microphase structure wherein island components, whichcontains a polymer differing from a cured resin constituting the seacomponent and are in the form of extremely fine particles at a nanometerlevel, are dispersed in the sea component containing the photo curedpolymer. As the results of further detailed studies on the structure andphysical properties of the thus obtained object by stereolithography, ithas been also found that an object by stereolithography, including photocured resin layers each having a sea-island microstructure, wherein fineisland components which contain a polymer differing from a cured resinconstituting the sea component and have a particle diameter of 20 to2,000 nm are dispersed in the sea component containing the curedpolymer, has a remarkably improved impact resistance compared with theexisting objects by stereolithography containing a single photo curedresin layer not having such a sea-island structure as described above.

The present inventors have also found that the impact resistance of theobject by stereolithography is further improved in the case where thepolymer constituting the island components in the sea-islandmicrostructure as described above has a glass transition temperature oflower than 40° C.

The present inventors have also found that a three-dimensional objecthaving not only an improved impact resistance but also a furtherimproved tensile strength and so on can be obtained in the case where,in each of the cured resin layers of the specific sea-islandmicrostructure as described above, the island components do not exist inthe upper portion located in the actinic radiation-irradiated surface ofeach cured resin layer but exist in a portion from the bottom part ofeach cured resin layer to an upward portion along the thicknessdirection of the each cured resin layer. This is because the upperportion having no island component contributes to the improvement of thetensile strength and so on.

The present inventors have also found that an object bystereolithography having the above-described sea-island microstructurecan be smoothly produced by stereolithography a composition prepared byhomogeneously blending an actinic radiation-curable resin compositioncontaining a the base component a polymerizable compound capable ofundergoing polymerization upon irradiation with an actinic radiationsuch as light with a polyalkylene ether compound having a number-averagemolecular weight of 500 to 10,000 as a component for forming thepolymeric island components, and that a cationic organic compound suchas an epoxy compound is preferred as a polymerizable compound forforming the photo cured sea component and the combined use of acationic-polymerizable organic compound such as an epoxy compound with aradical-polymerizable organic compound such as a (meth)acrylate compoundis still preferred.

The present inventors have furthermore found that, by using an oxetanecompound (in particular, an oxetane monoalcohol compound) in the actinicradiation-curable resin composition in producing a fabricated objecthaving the above-described sea-island microstructure with the use of theactinic radiation-curable resin composition containing acationic-polymerizable organic compound such as an epoxy compound, thereaction speed is elevated and thus the fabricating time can beshortened and, moreover, the sea-island structure comprising fine islandcomponents with a particle diameter of 20 to 2,000 nm can be smoothlyformed. The present invention has been completed based on these variousfindings.

Accordingly, the present invention relates to:

(1) A three-dimensional object comprising a plurality of cured resinlayers accumulated to each other, each of the cured resin layers havinga shaped pattern formed by irradiating a molding surface of an actinicradiation-curable resin composition with an actinic radiation, whereinthe three-dimensional object comprises at least cured resin layercomprising a sea-island microstructure in which island components aredispersed in a sea component comprising a cured polymer, the islandcomponents comprise a polymer differing from the cured resinconstituting the sea component, and the island components are fineisland components having a particle diameter of 20 to 2,000 nm.

The present invention further relates to:

(2) A three-dimensional object as described in the above (1), whereinall of the plurality of cured resin layers constituting thethree-dimensional object have the sea-island microstructure in whichisland components are dispersed in a sea component comprising a curedpolymer, the island components comprise a polymer differing from thecured resin constituting the sea component, and the island componentsare fine island components having a particle diameter of 20 to 2,000 nm;

(3) A three-dimensional object as described in the above (1) or (2),wherein each of the cured resin layers constituting thethree-dimensional object has a thickness of 10 to 500 μm;

(4) A three-dimensional object as described in any of the above (1) to(3) wherein, in each of the cured resin layers having the sea-islandmicrostructure, the island components do not exist in an upper portionof the each of the cured resin layers, the upper portion being locatedin an actinic radiation-irradiated surface of the each of the curedresin layers, and the island components exist in a portion from thebottom part of the each of the cured resin layers to an upward partalong the thickness direction of the each of the cured resin layers; or

(5) A three-dimensional object as described in the above (4), whereinthe upper portion containing no island component has a thickness of 2 to10% with respect to the thickness of the each of the cured resin layers.

The present invention further relates to:

(6) A three-dimensional object as described in any of the above (1) to(5), wherein each of the cured resin layers having the sea-islandmicrostructure has a sum of the island components of 1 to 30% by masswith respect to the mass of the each of the cured resin layers;

(7) A three-dimensional object as claimed in any of the above (1) to(6), wherein the polymer constituting the island components has a glasstransition temperature of lower than 40° C.; or

(8) A three-dimensional object as described in any of the above (1) to(7), wherein the polymer constituting the island components is apolyalkylene ether compound having a number average molecular weight of500 to 10,000.

The present invention further relates to:

(9) A three-dimensional object as described in any of the above (1) to(8), wherein the sea component comprises the cured resin formed by usingat least one actinic radiation-polymerizable compound selected from thegroup consisting of a cationic-polymerizable organic compound capable ofundergoing cationic polymerization upon irradiation with an actinicradiation and a radical-polymerizable organic compound capable ofundergoing radical polymerization upon irradiation with an actinicradiation;

(10) A three-dimensional object as described in any of the above (1) to(9), wherein the sea component comprises the cured resin formed by usingboth of a cation-polymerizable organic compound and aradical-polymerizable organic compound; or

(11) A three-dimensional object as described in the above (9) or (10),wherein the cation-polymerizable organic compound is a compound havingan epoxy group, and the radical-polymerizable organic compound is acompound having a (meth)acryl group.

The present invention further relates to:

(12) A method of producing a three-dimensional object having asea-island microstructure as described in the above (1), whichcomprises: irradiating a molding surface of an actinic radiation-curableresin composition with an actinic radiation to form a cured resin layerhaving a shaped pattern; and repeating a fabricating procedurecomprising: providing an actinic radiation-curable resin composition forone layer on a cured resin layer to form a molding surface; andirradiating the molding surface with an actinic radiation to form acured resin layer having a shaped pattern, so as to produce thethree-dimensional object comprising a plurality of cured resin layersaccumulated to each other, wherein the fabricating procedure isperformed by using an actinic radiation-curable resin compositioncomprising a homogeneous mixture of an actinic radiation-curable resincomponent with a component to become polymeric island components havinga particle diameter of 20 to 2,000 nm upon irradiation, and the actinicradiation-curable resin component is capable of forming a cured resin asa sea component upon the irradiation.

The present invention further relates to:

(13) A production method as described in the above (12), wherein theactinic radiation-curable resin composition comprises: at least oneactinic radiation-polymerizable compound as the cured resin of the seacomponent, the at lease one active ray-polymerizable compound beingselected from the group consisting of a cationic-polymerizable organiccompound capable of undergoing cationic polymerization upon irradiationwith an actinic radiation and a radical-polymerizable organic compoundcapable of undergoing radical polymerization upon irradiation with anactinic radiation; and a polyalkylene ether compound having anumber-average molecular weight of 500 to 10,000 as the polymer tobecome the polymeric island components; or

(14) A production method as described in the above (12) or (13), whereinthe cationic-polymerizable organic compound is a compound having anepoxy group and the radical-polymerizable organic compound is a compoundhaving a (meth)acryl group.

Moreover, the present invention relates to:

(15) A production method as described in any of the above (12) to (14),wherein a content of the polymer to become the polymeric islandcomponents is from 1 to 30% by mass with respect to the mass of theactinic radiation-curable resin composition used for forming the curedresin layer having the sea-island microstructure; or

(16) A production method as described in any of the above (12) to (15),wherein the actinic radiation-curable resin composition contains anoxetane compound together with a cationic-polymerizable organic compoundhaving an epoxy group.

In the three-dimensional object according to the present invention, eachof the cured resin layers constituting the three-dimensional object hasa unique sea-island microstructure wherein fine island components whichcontain a polymer differing from a cured resin constituting the seacomponent and have a particle diameter of 20 to 2,000 nm are dispersedin the sea component containing the cured polymer. Thus, thisthree-dimensional object (object by stereolithography) is much superiorin toughness to the existing objects by stereolithography(three-dimensional objects) and, in its turn, has an extremely superiorimpact resistance.

In addition to the high impact resistance as described above, thethree-dimensional object according to the present invention is superiorin dimensional stability, mechanical properties such as tensile strengthand other properties such as water resistance, moisture resistance andheat resistance. Owing to these characteristics, it is effectivelyusable not only for typical prototype models but also for actual partsfor practical use, e.g., actual components.

The three-dimensional object according to the present invention havingthe specific sea-island microstructure and superior properties asdiscussed above can be smoothly produced by the production methodaccording to the present invention.

BREIF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing schematically showing an example of the sea-islandmicrostructure of the three-dimensional object according to the presentinvention.

FIG. 2 is a drawing of a microscopic photograph showing the state of asection of the three-dimensional object according to the presentinvention obtained in EXAMPLE 1.

FIG. 3 is a drawing of a microscopic photograph showing the state of asection of the three-dimensional object obtained in COMPARATIVE EXAMPLE1.

In these figures, a stands for a sea component made of cured resin; bstands for an island component; and c stands for an island-free part ofa cured resin layer.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present invention will be illustrated in greater detail.

A three-dimensional object according to the present invention is athree-dimensionally object formed by accumulating a plurality of curedresin layers which have a shaped pattern s formed by irradiating amolding surface of an actinic radiation-curable resin composition withan actinic radiation.

The term “actinic radiation” as used in this specification means anenergy beam capable of curing a resin composition for stereolithographysuch as ultraviolet ray, electron beam, X-ray or radial ray.Accordingly, the term “actinic radiation-curable resin composition” tobe used in producing a three-dimensional object according to the presentinvention means a resin composition which is cured upon irradiation withone or more actinic radiations (energy beams) as described above.

In a three-dimensional object according to the present invention, atleast part of the plurality (a large number) of cured resin layersconstituting the three-dimensional object (i.e., all or some of theplurality of cured resin layers) have a sea-island microstructurewherein fine island components which contain a polymer differing from acured resin constituting the sea component and have a particle diameterof 20 to 2,000 nm are dispersed in the sea component of the curedpolymer.

In the case where the particle diameter of the island component is lessthan 20 nm, the impact resistance of the three-dimensional object islowered. In the case where the particle diameter thereof exceeds 2,000nm, on the other hand, the mechanical properties such as mechanicalstrength are lowered. The particle diameter of the island componentpreferably ranges from 30 to 1,500 nm, still preferably from 40 to 1,000nm and still preferably from 50 to 500 nm.

The expression “all of the plurality of cured resin layers constitutingthe three-dimensional object have a sea-island microstructure whereinisland components are dispersed in a sea component of the cured resin”means that all layers of the plurality (a large number) of cured resinlayers constituting the three-dimensional object individually have thesea-island microstructure as described above.

The expression “some of the plurality of cured resin layers constitutingthe three-dimensional object have a sea-island microstructure whereinisland components are dispersed in a sea component of the cured resin”means that part (some layers) of the plurality (a large number) of curedresin layers constituting the three-dimensional object individually havethe sea-island microstructure as described above while the remainder ofthe cured resin layers have a structure containing no island component(a non-sea-island structure).

In a three-dimensional object according to the present invention, it isfavorable from the viewpoint of achieving a favorable impact resistanceof the whole three-dimensional object that all layers of the cured resinlayers constituting the three-dimensional object have the microstructurewherein fine island components which have a particle diameter of 20 to2,000 nm are dispersed in the sea component made of the cured polymer.

In a three-dimensional object according to the present invention, thethickness of a single cured resin layer may vary depending on the typeand composition ratio of the actinic radiation-curable resin compositionto be used in producing the three-dimensional object, the type andenergy intensity of the actinic radiation, the fabricating speed and soon. By considering the type and energy intensity of the actinicradiation, the fabricating speed, the fabricating accuracy, themechanical properties of the obtained three-dimensional object and soon, it is generally preferable that the thickness ranges from 10 to 500μm, still preferably from 30 to 300 μm and still preferably from 50 to200 μm. In the case where the thickness of a single cured resin layer isless than 10 μm, a fabricating procedure of forming an extremely largenumber of cured resin layers layer by layer is required for producing athree-dimensional object and thus a long fabricating time is required,i.e., being impractical. In the case where the thickness of a singlecured resin layer exceeds 500 μm, on the other hand, the obtainedthree-dimensional object frequently suffers from lowering in thefabricating accuracy, the dimensional accuracy and the mechanicalproperties.

In a single cured resin layer (each cured resin layer) of athree-dimensional object according to the present invention, the islandcomponents may be evenly or almost evenly dispersed in each cured resinlayers. Alternatively, the island components may be unevenly distributedin each cured resin layer.

Preferred examples of a mode wherein the island components are unevenlydispersed in each cured resin layer include a mode wherein the islandcomponents do not exist in the upper portion located in the actinicradiation-irradiated surface of the cured resin layer but are dispersedin a portion from the bottom part of the cured resin layer to an upwardpart along the thickness direction of the cured resin layer. In such amode with uneven distribution, it is preferred that the islandcomponents do not exist in the upper portion corresponding to from 2 to10% of the thickness of a single layer from the actinicradiation-irradiated surface but are dispersed in the lower portion(i.e., the portion corresponding to 98 to 90% of the thickness of eachcured resin layer). In the mode with the uneven distribution asdescribed above, the upper thickness portion having no island component(preferably the thickness portion corresponding to 2 to 10% as describedabove) contributes to the impartment of mechanical strength such astensile strength to the three-dimensional object, whereas the lowerthickness portion having the island components dispersed therein(preferably the thickness portion corresponding to 98 to 90% asdescribed above) contributes to the impartment of impact resistance tothe three-dimensional object. Consequently, a three-dimensional objectbeing superior in mechanical strength such as tensile strength andimpact resistance can be obtained.

Based on the illustration as discussed above, the layer structure in thevertical section of the three-dimensional object according to thepresent invention will be illustrated by reference to FIG. 1 (theappearance of the three-dimensional object being omitted), though theinvention is not restricted thereto.

FIG. 1(i) shows an example of a mode wherein island components b arealmost evenly distributed in the sea components a in all of the curedresin layers (L₁ to L_(m+n)) constituting the three-dimensional object.

FIG. 1(ii) shows an example of another mode wherein island components bare distributed in the sea components a in all of the cured resin layers(L₁ to L_(m+n)) constituting the three-dimensional object but, in eachcured resin layer, the island components b do not exist in the upperportion (the part c) located in the actinic radiation-irradiated surfacebut are unevenly dispersed in the lower portion thereof.

From the viewpoints of the tensile strength, impact resistance, heatresistance and so on of the three-dimensional object, it is preferablein a three-dimensional object according to the present invention that,in each of the cured resin layers having the sea-island microstructure,the sum of the island components contained in each cured resin layer isfrom 1 to 30% by mass, still preferably from 5 to 25% by mass, withrespect to the mass of the cured resin layer having the sea-islandmicrostructure. In the case where the sum of the island components ineach cured resin layer having the sea-island microstructure is less than1% by mass, it is frequently observed that only an insufficient effectof improving the impact resistance of the three-dimensional object canbe obtained. In the case where the sum thereof exceeds 30% by mass, onthe other hand, it is frequently observed that the tensile strength,hardness, heat resistance and so on of the three-dimensional object areworsened.

In a three-dimensional object according to the present invention, thepolymer forming the island components may be dispersed in the seacomponent in the state of being bonded (for example, chemically bonded)to the polymer forming the sea component. Alternatively, it may bedispersed in the sea component in a separated state without being bondedto the polymer forming the sea component.

In a three-dimensional object according to the present invention, thepolymer forming the island components may be an arbitrary polymer solong as it can be sedimented and dispersed as island components of 20 to2,000 nm in particle diameter in the sea component of the cured resinwhen irradiated with the actinic radiation. As the polymer for formingthe island components, it is generally preferable to employ a polymerhaving a chain-type or almost chain-type structure which can behomogeneously mixed (preferably dissolved) in the actinicradiation-curable resin composition for forming the cured resin layerhaving the sea-island microstructure.

In a three-dimensional object according to the present invention, it ispreferable from the viewpoint of improving the impact resistance,flexibility and so on of the three-dimensional object that the islandcomponents are made of a polymer having a glass transition temperaturelower than 40° C. It is still preferable that the island components aremade of a polymer having a glass transition temperature lower than 30°C., still preferably a polymer having a glass transition temperaturelower than 20° C. In the case where the glass transition temperature ofthe polymer forming the island components is excessively high, athree-dimensional object having a superior impact resistance can behardly obtained.

The term “glass transition temperature” as used in this specificationmeans the glass transition temperature that is measured by using thepolymer forming the island components alone without dispersing thepolymer in the sea component. This glass transition temperature ismeasured as the temperature Tg(° C.) detected at the specific heatdeflection point in the DSC measurement of the polymer or as thetemperature derived from the maximum peak of tan δ measured with adynamic viscoleastometer, namely, the point at which the elastic modulusshows a rapid decrease.

In a three-dimensional object according to the present invention, it ispreferable that the island components are made of a polyalkylene ethercompound having a number-average molecular weight of 500 to 10,000,still preferably a polyalkylene ether compound having a number-averagemolecular weight of 1,000 to 5,000 from the viewpoint that the fineisland components having a particle diameter of 20 to 2,000 nm can befavorably dispersed in the sea component made of the cured resin. Theterm “a polyalkylene ether compound” as used herein means a compoundcomprising multiple oxyalkylene units (alkylene ether units) (—R—O—(wherein R is an alkylene group)) of the same or different types bondedtogether or its derivative. The number-average molecular weight of thepolyalkylene ether compound as used herein means the number-averagemolecular weight measured by the gel permeation chromatography (GPC)with the use of polystyrene as the standard.

In a three-dimensional object according to the present invention, it isparticularly preferable that the island components are made of apolyalkylene ether compound represented by the following general formula(I):A-O—(R¹—O—)_(m)—(R²—O—)_(n)-A′  (I)wherein R¹ and R² are different from each other and each represents astraight-chain or branched alkylene group having from 2 to 10 carbonatoms; A and A′ independently represent each a hydrogen atom, an alkylgroup, a phenyl group, an acetyl group or a benzoyl group; and m and nindependently represent each 0 or an integer of 1 or above (providedthat at least one of m and n does not represent 0).

In the case where both of m and n in the polyalkylene ether compoundrepresented by the above general formula (I) (hereinafter sometimesreferred to as the polyalkylene ether compound (I)) are integers of 1 orabove and the sum of m and n is 3 or above, the oxyalkylene unit(alkylene ether unit): —R¹—O— and the oxyalkylene unit (alkylene etherunit): —R²—O— may be bonded either via random bond or via block bond.Alternatively, a mixture of random bond with block bond may be employed.

In the above-described polyalkylene ether compound (I), specificexamples of R¹ and R² include an ethylene group, an n-propylene group,an isopropylene group, an n-butylene group (a tetramethylene group), anisobutylene group, a tert-butylene group, straight-chain or branchedpentylene groups (for example, —CH₂CH₂CH₂CH₂CH₂— and—CH₂CH₂CH(CH₃)CH₂—), straight-chain or branched hexylene groups (forexample, —CH₂CH₂CH₂CH₂CH₂CH₂—, —CH₂CH₂CH(CH₃)CH₂CH₂— and—CH₂CH₂CH(C₂H₅)CH₂—), heptylene groups, octylene groups, nonylenegroups, decanylene groups and so on. Among them, it is preferred that R¹and R² are any groups selected from among ethylene group, an n-propylenegroup, an isopropylene group, an n-butylene group (a tetramethylenegroup), an n-pentylene group, a branched pentylene group represented bythe formula —CH₂CH₂CH(CH₃)CH₂—, an n-hexylene group and branchedhexylene groups represented by the formula: —CH₂CH₂CH(CH₃)CH₂CH₂— or—CH₂CH₂CH(C₂H₅)CH₂—.

In the above-described polyalkylene ether compound (I), specificexamples of A and A′ include a hydrogen atom, a methyl group, an ethylgroup, a propyl group, a butyl group, a phenyl group, an acetyl group, abenzoyl group and so on. Among them, it is preferred that at least oneof them, in particular, both of them are hydrogen atoms. In the casewhere at least one of A and A′ is a hydrogen atom, the hydroxyl groupsat both ends of the polyalkylene ether compound react with the resincomponent forming the sea component upon the irradiation of the actinicradiation-curable resin composition containing the polyalkylene ethercompound with the actinic radiation to form a single cured resin layer.As a result, the island components formed by the polyalkylene ethercompound, which has been bonded to the cured resin forming the seacomponent, are stable dispersed in the sea component.

In the above-described polyalkylene ether compound (I), it is preferredthat m and n respectively showing the numbers of the repeatingoxyalkylene units are such values as controlling the number-averagemolecular weight of the polyalkylene ether compound within the range of500 to 10,000.

Appropriate examples of the above-described polyalkylene ether compound(I) include polyethylene glycol, polypropylene glycol,polytetramethylene glycol, polyethylene oxide-polypropylene oxide blockcopolymer, ethylene oxide-propylene oxide random copolymer, a polyethercomprising oxytetramethylene units having alkyl substituent(tetramethylene ether units having alkyl substituent) represented by theformula: —CH₂CH₂CH(R⁵)CH₂O— (wherein R⁵ represents a lower alkyl group,preferably a methyl or ethyl group) bonded together, a polyethercomprising oxytetramethylene units and the above-describedoxytetramethylene units having alkyl substituent represented by theformula: —CH₂CH₂CH(R⁵)CH₂O— (wherein R⁵ is as defined above) bondedtogether at random, and so on. The island components may be made of oneof the above-described polyalkylene ether compounds or two or morethereof, so long as the island component mass does not exceeds thecomposition ratio as described above.

Among them, it is preferred to use polytetramethylene glycol having anumber-average molecular weight of 500 to 10,000 as described aboveand/or a polyether comprising teramethylene ether units withtetramethylene ether units having alkyl substituent represented by theformula: —CH₂CH₂CH(R⁵)CH₂O— (wherein R⁵ is as defined above) bondedtogether at random, since fine island components having a particlediameter of 20 to 2,000 nm can be easily formed in the island componentmade of the cured resin to give a three-dimensional object having a lowhygroscopicity and being superior in dimensional stability andmechanical stability.

Each of the cured resin layers constituting the three-dimensional object(in particular, the sea component in a cured resin layer having thesea-island microstructure) may be made of any of activeenergy-polymerizable (curable) organic compounds having been employed instereolithographic techniques with the use of actinic radiations. Amongthem, it is preferable that the cured resin layer is made of a curedresin which is formed by using at lease one of a cationic-polymerizableorganic compound capable of undergoing cationic polymerization uponirradiation with an actinic radiation and a radical-polymerizableorganic compound capable of undergoing radical polymerization uponirradiation with an actinic radiation. It is still preferable that thecured resin layer is made of a cured resin which is formed by using bothof a cationic-polymerizable organic compound and a radical-polymerizableorganic compound, from the viewpoints of the dimensional stability, heatresistance, moisture resistance, mechanical properties and so on of thethree-dimensional object.

As the cationic-polymerizable organic compound in this step, use may bemade of any compound capable of undergoing a polymerization reactionand/or a crosslinkage reaction upon irradiation with an actinicradiation in the presence of an actinic radiation-sensitive cationicpolymerization initiator. Typical examples thereof include epoxycompounds, cyclic ether compounds, cyclic acetal compounds, cycliclactone compounds, cyclic thioether compounds, spiroorthoestercompounds, vinyl ether compounds and so on. In the present invention usemay be made of either one or more of the cationic-polymerizable organiccompounds as described above.

Specific examples of the cationic-polymerizable organic compound are asfollows:

(1) epoxy compounds such as alicyclic epoxy resins, aliphatic epoxyresins and aromatic epoxy resins;

(2) trimethylene oxide, oxetane compounds such as 3,3-dimethyloxetane,3,3-dichloromethyloxetane, 3-methyl-3-phenoxymethyloxetane and1,4-bis((3-ethyl-3-oxetanylmethoxy)methyl)benzene, oxolane compoundssuch as tetrahydrofuran and 2,3-dimethyltetrahydrofuran and cyclic etheror cyclic acetal compounds such as trioxane, 1,3-dioxolane and1,3,6-trioxane cyclooctane;

(3) cyclic lactone compounds such as β-propiolactone and ε-caprolactone;

(4) thiirane compounds such as ethylene sulfide and thioepichlorohydrin;

(5) thiethane compounds such as 1,3-propyn sulfide and3,3-dimethylthiethane;

(6) vinyl ether compounds such as ethylene glycol divinyl ether, alkylvinyl ether, 3,4-dihydropyran-2-methyl (3,4-dihydropyran-2-carboxylate)and triethylene glycol divinyl ether;

(7) spiroorthoester compounds obtained by reacting an epoxy compoundwith a lactone;

(8) ethylenically unsaturated compounds such as vinyl cyclohexane,isobutylene and polybutadiene; and so on.

Among the above-described compounds, it is preferred to use an epoxycompound as the cationic-polymerizable organic compound for forming thesea component. It is still preferable to use a polyepoxy compound havingtwo or more epoxy groups per molecule. By using epoxy compounds (amixture of epoxy compounds) containing an alicyclic polyepoxy compoundhaving two or more epoxy groups per molecule and the content of thealicyclic polyepoxy compound being 30% by weight or more, stillpreferably 50% by weight or more, with respect to the total weight ofthe epoxy compounds as the cationic-polymerizable organic compound, inparticular, it is possible to further improve the cationicpolymerization speed, the thick film curability, the resolution, theactinic radiation permeability and so on in the production of thethree-dimensional object. In this case, moreover, the viscosity of theactinic radiation-curable resin composition is lowered and, therefore,molding can be smoothly carried out. As a result, the obtainedthree-dimensional object has a further lowered volume shrinkage.

Examples of the alicyclic epoxy resin as described above includepolyglycidyl ether of a polyhydric alcohol having at least one alicyclicring, a cyclohexene oxide or cyclopentene oxide-containing compoundobtained by epoxidizing a cyclohexne or cyclopentene ring-containingcompound with an appropriate oxidizing agent such as hydrogen peroxideor a peracid, and so on. More specifically speaking, examples of thealicyclic epoxy resin include hydrogenated bisphenol A diglycidyl ether,3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate,2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meth-dioxane,bis(3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene dioxide,4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3,4-epoxy-6-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadienediepoxide, di(3,4-epoxycyclohexylmethyl) ether of ethylene glycol,ethylenebis(3,4-epoxycyclohexane carboxylate), dioctylepoxyhexahyrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate and soon.

Examples of the above-described aliphatic epoxy resin includehomopolymers and copolymers of polyglycidyl ether of an aliphaticpolyhydric alcohol or its alkylene oxide adduct and polyglycidyl ester,glycidyl acrylate or glycidyl methacrylate of an aliphatic long-chainpolybasic acid and so on. More specifically speaking, examples thereofinclude diglycidyl ether of 1,4-butanediol, diglycidyl ether of1,6-hexanediol, triglycidyl ether of glycerol, triglycidyl ether oftrimethylolpropane, tetraglycidyl ether of sorbitol, hexaglycidyl etherof dipentaerythritol, diglycidyl ether of polyethylene glycol,diglycidyl ether of polypropylene glycol, polyglycidyl ether of apolyether polyol obtained by adding one or more alkylene oxides to analiphatic polyhydric alcohol such as ethylene glycol, propylene glycolor glycerol, diglycidyl ether of an aliphatic long-chain dibasic acidand so on. In addition to the above-described epoxy compounds, citationmay be made of, for example, monoglycidyl ether of an aliphatic higheralcohol, diglycidyl ether of a higher fatty acid, epoxidized soybeanoil, butyl epoxystearate, octyl epoxystearate, epoxidized linseed oil,epoxidized polybutadiene and so on.

Examples of the above-described aromatic epoxy resin include a mono- orpolyglycidyl ether of a monohydric or polyhydric phenol having at leastone aromatic nucleus or its alkylene oxide. More specifically speaking,examples thereof include a glycidyl ether obtained by reacting bisphenolA, bisphenol F or an alkylene oxide adduct thereof with epichlorohydrin,epoxy novolac resin, phenol, cresol butylphenol or monoglycidyl ether ofa polyether alcohol obtained by adding an alkylene oxide thereto, and soon.

The sea component in a cured resin layer of the three-dimensional objectcan be formed by using one or more epoxy compounds as described above.As described above, it is particularly preferred that the sea componentis formed by using epoxy compounds containing a polyepoxy compoundhaving two or more epoxy groups per molecule at a ratio of 30% by weightor more.

As the radical-polymerizable organic compound, use may be made of anycompound capable of undergoing a polymerization reaction and/or acrosslinkage reaction upon irradiation with an actinic radiation in thepresence of an actinic radiation-sensitive radical polymerizationinitiator. Typical examples thereof include compounds having(meth)acrylate group, unsaturated polyester compounds, allylurethanecompounds, polythiol compounds and so on. Use can be made of one or moreof the radical-polymerizable organic compounds as described above. Amongthem, it is preferable to use a compound having at least one (meth)acrylgroup. Specific examples thereof include a product of a reaction betweenan epoxy compound with (meth)acrylic acid, (meth)acrylic acid esters ofalcohols, urethane (meth)acrylate, polyester (meth)acrylate, polyether(meth)acrylate and so on.

Examples of the above-described product of a reaction between an epoxycompound with (meth)acrylic acid include (meth)acrylate type reactionproducts obtained by reacting an aromatic epoxy compound, an alicyclicepoxy compound and/or an aliphatic epoxy compound with (meth)acrylicacid. Among the (meth)acrylate type reaction products as describedabove, (meth)acrylate type reaction products obtained by reacting anaromatic epoxy compound with (meth)acrylic acid are preferably employed.Specific examples thereof include (meth)acrylate obtained by reacting aglycidyl ether, which is obtained by reacting a bisphenol compound suchas bisphenol A or bisphenol S or its alkylene oxide adduct with anepoxidizing agent such as epichlorohydrin, with (meth)acrylic acid, a(meth)acrylate type reaction product obtained by epoxy novolac resinwith (meth)acrylic acid and so on.

Examples of the (meth)acrylic acid esters of alcohols as described aboveinclude (meth)acrylates obtained by reacting an aromatic alcohol, analiphatic alcohol, an alicyclic alcohol and/or an alkylene oxide adductthereof having at least one hydroxyl group per molecule with(meth)acrylic acid.

More specifically speaking, examples thereof include 2-ethylhexyl(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isooctyl(meth)acrylate, tetrahydrofuryl (meth)acrylate, isobornyl(meth)acrylate, benzyl (meth)acrylate, 1,4-butanediol di(meth)acrylate,1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate,polyethylene glycol di(meth)acrylate, polypropylene glycoldi(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritoltri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, (meth)acrylatesof alkylene oxides of polyhydric alcohols such as diols, triols,tetraols and hexaols as described above, and so on.

Among them, use may be preferably made of a (meth)acrylate obtained byreacting a polyhydric alcohol with (meth)acrylic acid and having two ormore (meth)acryl groups per molecule as an alcohol (meth)acrylate.

Among the (meth)acrylate compounds as described above, acrylatecompounds are preferred to methacrylate compounds from the viewpoint ofthe polymerization speed.

Examples of the urethane (meth)acrylate as described above include(meth)acrylate obtained by reacting a hydroxyl group-containing(meth)acrylic acid ester with an isocyanate compound. As theabove-described hydroxyl group-containing (meth)acrylic acid ester, ahydroxyl group-containing (meth)acrylic acid ester obtained by anesterification reaction between an aliphatic dihydric alcohol with(meth)acrylic acid. Specific examples thereof include 2-hydroxyethyl(meth)acrylate and so on. As the above-described isocyanate compound, apolyisocyanate compound having two or more isocyanate groups permolecule such as tolylene diisocyanate, hexamethylene diisocyanate orisophorone diisocyanate is preferred.

Examples of the above-described polyester (meth)acrylate includepolyester (meth)acrylates obtained by reacting a hydroxylgroup-containing polyester with (meth)acrylic acid.

Examples of the above-described polyether (meth)acrylate includepolyether (meth)acrylates obtained by reacting a hydroxylgroup-containing polyether with (meth)acrylic acid.

A three-dimensional object according to the present invention isproduced by using an actinic radiation-curable resin compositioncontaining a homogeneous mixture of an actinic radiation-curable resincomponent, which is capable of forming a cured resin as a sea componentupon irradiation with an actinic radiation, with a component aspolymeric island components having a particle diameter of 20 to 2,000 nmupon irradiation with an actinic radiation.

An actinic radiation-curable resin composition to be used in aproduction method according to the present invention may be any actinicradiation-curable resin composition so long as it contains a polymer(curable) component capable of forming the sea component in theformation of a single cured resin layer by irradiating a molding surfaceof an actinic radiation-curable resin composition with an actinicradiation, together with a polymeric component that can be sedimentedand dispersed as island components having the specific particle diameteras described above.

In the above-described actinic radiation-curable resin composition to beused in the present invention, it is preferable that the content of thepolymeric component as the island components corresponds to from 1 to30% by mass, still preferably from 5 to 25% by mass, based on the massof the actinic radiation-curable resin composition to be used forforming the cured resin layer having the sea-island microstructure. Inthe case where the content of the component as the polymeric islandcomponents is less than 1% by mass, the number and area of the islandcomponents are lessened and thus a three-dimensional object beingsuperior in impact resistance and so on can be hardly obtained. In thecase where the content thereof exceeds 30% by mass, on the other hand,it is frequently observed that the tensile strength, hardness, heatresistance and so on of the three-dimensional object are worsened.

In the present invention, it is preferable to use an actinicradiation-curable resin composition which contains at least one actinicradiation-polymerizable compound selected from a cationic-polymerizableorganic compound capable of undergoing cationic polymerization uponirradiation with an actinic radiation and a radical-polymerizableorganic compound capable of undergoing radical polymerization uponirradiation with an actinic radiation as the actinic radiation-curableresin component forming the cured resin serving as the sea component,and a polyalkylene ether compound having a number-average molecularweight of 500 to 10,000 as the component serving as the polymeric islandcomponents. It is particularly preferred to use an actinicradiation-curable resin composition which contains both of acationic-polymerizable organic compound and a radical-polymerizableorganic compound and a polyalkylene ether compound having anumber-average molecular weight of 500 to 10,000, as the actinicradiation-curable resin components forming the island components. As thepolyalkylene ether compound, use is preferably made of polyalkyleneether compounds represented by the above general formula (I). By usingsuch an actinic radiation-curable resin composition, a cured resin layerhaving the sea-island microstructure wherein island components ofextremely fine polymer particles of 20 to 2,000 nm in particle diameterare dispersed in the sea component made of the cured resin.

As the cationic-polymerizable organic compound and theradical-polymerizable organic compound in the actinic radiation-curableresin composition as described above, use can be made of one or more ofvarious cationic-polymerizable organic compounds andradical-polymerizable organic compounds as specifically cited above.

The actinic radiation-curable resin composition containing thecationic-polymerizable organic compound and/or the radical-polymerizableorganic compound contains an actinic radiation-sensitive cationicpolymerization initiator (hereinafter sometimes referred to simply as “acationic polymerization initiator”) and/or an actinicradiation-sensitive radical polymerization initiator (hereinaftersometimes referred to simply as “a radical polymerization initiator”).

As the cationic polymerization initiator, any polymerization initiatorcapable of initiating the cationic polymerization of thecationic-polymerizable organic compound can be used. Among all, it ispreferable to use an onium salt releasing a Lewis acid upon the actinicradiation irradiation as the cationic polymerization initiator. Examplesof such an onium salt include aromatic sulfonium salts of the group VIIaelements, aromatic onium salts of the group Via elements, aromatic oniumsalts of the group Va elements and so on. More specifically speaking,examples thereof include triphenylphenacylphosphonium tetrafluoroborate,triphenylphosphonium hexafluoroantimonate,bis-(4-(diphenylsulfonio)phenyl)sulfide bisdihexafluoroantimonate,bis-(4-(di4′-hydroxyethoxyphenylsulfonio)phenyl)sulfidebisdihexafluoroantimonate, bis-(4-(diphenylsulfonio)phenyl)sulfidebisdihexafluorophosphate, diphenyliodonium tetrafluoroborate and so on.

Either one of the above-described cationic polymerization initiators ora combination of two or more thereof may be used. It is also possible touse one or more of the cationic polymerization initiators as describedabove together with another cationic polymerization initiator.

In order to elevate the reaction speed, it is also possible to add thecationic polymerization initiator together with a photosensitizer suchas benzophenone, benzoyl alkyl ether or thioxanthone, if required.

As the radical polymerization initiator, any polymerization initiatorcapable of initiating the radical polymerization of theradical-polymerizable organic compound upon the actinic radiationirradiation can be used. Examples thereof include benzyl or its dialkylacetal compounds, acetoxyphenone compounds, benzoin or its alkyl ethercompounds, benzophenone compounds, thioxanthone compounds and so on.

More specifically speaking, examples of the benzyl or its dialkyl acetalcompounds include benzyl dimethyl ketal, benzyl-α-methoxyethyl acetal,1-hydroxycyclohexyl phenyl ketone and so on.

Examples of the acetophenone compounds include diethoxyacetophenone,2-hydroxymethyl-1-phenylpropan-1-one,4′-isopropyl-2-hydroxy-2-methyl-propiophenone,2-hydroxy-2-methyl-propiophenone, p-dimethylaminoacetophenone,p-tert-butyldichloroacetophenone, p-tert-butyltrichloroacetophenone,p-azidobenzalacetophenone and so on.

Examples of the benzoin compounds include benzoin, benzoin methyl ether,benzoin ethyl ether, benzoin isopropyl ether, benzoin normal-butylether, benzoin isobutyl ether and so on.

Examples of the benzophenone compounds include benzophenone, methylo-benzoylbenzoate, Michler's ketone, 4,4′-bisdiethylaminobenzophenone,4,4′-dichlorobenzophenone and so on.

Examples of the thioxanthone compounds include thioxanthone,2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone,2-isopropylthioxanthone and so on.

Either one of these radical polymerization initiators or a combinationof two or more thereof may be used.

In the case where the actinic radiation-curable resin compositioncontains a cationic-polymerizable organic compound, in particular, thecase of containing an epoxy compound as the cationic-polymerizableorganic compound, the cationic-polymerizable organic compound shows alow reaction speed and, therefore, a long time is required forfabricating. Thus, it is favorable to add an oxetane compound thereto soas to promote the cationic polymerization. By adding an oxetanecompound, in particular, an oxetane monoalcohol compound to an actinicradiation-curable resin composition containing a cationic-polymerizableorganic compound comprising an epoxy compound, moreover, it is possibleto smoothly produce a three-dimensional object having the microstructurewherein island components having a particle diameter of 20 to 2,000 nmare dispersed in the sea component made of a cured resin.

As the oxetane compound, use may be preferably made of an oxetanemonoalcohol compound having one or more oxetane groups and one alcoholichydroxyl group per molecule. It is particularly preferable to use anoxetane monoalcohol compound represented by the following generalformula (II).

wherein R³ represents an alkyl group, an aryl group or an aralkyl group;and p represents an integer of 1 to 6.

Examples of R³ in the above general formula (II) include alkyl groupshaving from 1 to 10 carbon atoms such as methyl, ethyl, propyl, butyl,pentyl, hexyl, heptyl, octyl, nonyl and decyl, aryl groups such asphenyl, tolyl, naphthyl, methylphenyl and naphthyl, and aralkyl groupssuch as benzyl and β-phenylethyl. Among them, it is preferable that R³is a lower alkyl group such as methyl, ethyl, propyl or butyl.

In the above general formula (II), p is an integer of 1 to 6, preferablyan integer of 1 to 4.

Specific examples of the oxetane monoalcohol compound represented by theabove general formula (11) include 3-hydroxymethyl-3-methyloxetane,3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane,3-hydroxymethyl-3-normal-butyloxetane, 3-hydroxymethyl-3-phenyloxetane,3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane,3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane,3-hydroxyethyl-3-phenyloxetane, 3-hydroxypropyl-3-methyloxetane,3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane,3-hydroxypropyl-3-phenyloxetane, 3-hydroxybutyl-3-methyloxetane and soon. Either one of these compounds or two or more thereof may be used.Among them, it is preferable to use 3-hydroxymethyl-3-methyloxetane or3-hydroxymethyl-3-ethyloxetane from the viewpoint of availability, etc.

In producing a three-dimensional object according to the presentinvention by using an actinic radiation-curable resin compositioncontaining a cationic-polymerizable organic compound and aradical-polymerizable organic compound together with a component servingas the polymeric island components, it is preferable from the viewpointsof the viscosity of the composition, the reaction speed, the fabricatingspeed, the dimensional accuracy and mechanical properties of theobtained three-dimensional object and so on that the compositioncontains the cationic-polymerizable organic compound and theradical-polymerizable organic compound at the ratio by mass of thecationic-polymerizable organic compound: the radical—polymerizableorganic compound of 90:10 to 30 to 70, still preferably at a ratio bymass of 80:20 to 40:60.

It is preferred that the actinic radiation-curable resin composition asdescribed above contains a cationic polymerization initiator in anamount of 1 to 10% by mass, based on the total mass of thecationic-polymerizable organic compound and the radical-polymerizableorganic compound, and a radical polymerization initiator in an amount of0.5 to 10% by mass. It is still preferable that the composition containsfrom 2 to 6% by mass of the cationic polymerization initiator and from 1to 5% by mass of the radical polymerization initiator.

In the case where the actinic radiation-curable resin compositioncontains an oxetane monoalcohol compound, the content of the compoundpreferably ranges from 1 to 30% by mass, still preferably from 2 to 20%by mass, based on the mass of the cationic polymerization initiator. Bycontrolling the content of the oxetane monoalcohol compound within therange as specified above, a three-dimensional object in which the islandcomponents having a particle diameter of 20 to 2,000 nm are dispersed inthe sea component made of the cured resin and which is superior inmechanical properties, in particular, impact resistance, dimensionalstability, water resistance, moisture resistance, heat resistance and soon can be smoothly produced at a high fabricating speed.

By using an actinic radiation-curable resin composition containing aradical-polymerizable organic compound, a cationic-polymerizable organiccompound comprising an epoxy compound, a radical polymerizationinitiator and a cationic polymerization initiator and further containinga polyalkylene ether compound represented by the above-described generalformula (I) and an oxetane monoalcohol compound as the actinicradiation-curable resin composition, in particular, thethree-dimensional object according to the present invention having thesea-island microstructure wherein the island components having aparticle diameter of 20 to 2,000 nm are dispersed in the sea componentmade of the cured resin can be smoothly produced.

The above-described actinic radiation-curable resin compositioncontaining a cationic-polymerizable organic compound such as an epoxycompound, which is appropriately usable in the present invention, maycontain, if desired, an oxetane compound having two or more oxetanegroups per molecule but having no alcoholic hydroxyl group (hereinaftersometimes referred to as “a polyoxetane compound”) together with theoxetane monoalcohol compound as described above. By adding thepolyoxetane compound, the dimensional stability of the obtainedthree-dimensional object is further improved and the above-describedsea-island microstructure can be favorably expressed. In the case ofadding the polyoxetane compound, the content thereof preferably rangesfrom 50 to 200% by mass based on the mass of the oxetane monoalcoholcompound as described above.

As examples of the polyoxetane compound, compounds represented by thefollowing general formula (III) may be cited.

wherein R⁴ represents a hydrogen atom, a fluorine atom, an alkyl group,a fluoroalkyl group, an aryl group or an aralkyl group; E represents anoxygen atom or a sulfur atom; q represents an integer of 2 or above; andG represents a divalent or higher organic group.

In the above-described general formula (III), examples of R⁴ include ahydrogen atom, a fluorine atom, alkyl groups having from 1 to 10 carbonatoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, nonyl and decyl, fluoroalkyl groups substituted by one or morefluorine atoms and having from 1 to 6 carbon atoms such as fluoromethyl,fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl and fluorohexyl,aryl groups such as phenyl, tolyl, naphthyl, methylphenyl and naphthyl,aralkyl groups such as benzyl and β-phenylethyl and a furyl group. Amongall, it is preferred that R⁴ is a hydrogen atom or a lower alkyl groupsuch as methyl, ethyl, propyl, butyl, pentyl or hexyl.

It is preferred that q is an integer of 2 to 4.

The valency G is the same as the numerical value q. Examples of Ginclude alkylene groups having from 1 to 12 carbon atoms, divalentarylene groups such as a phenylene group and a bisphenol residue,diorganopolysiloxy groups, trivalent or tetravalent hydrocarbon groupsand so on.

Appropriate examples of the compound having two or more oxetane groupsper molecule include 1,4-bis((3-ethyl-3-oxetanylmethoxy)methyl)benzene,1,4-bis(3-ethyl-3-oxetanylmethoxy)butane and so on.

An actinic radiation-curable resin composition to be used in the presentinvention may further contain, if desired, appropriate amount of one ormore additives, for example, a coloring agent such as a pigment or adye, a defoaming agent, a leveling agent, a thickener, a flameretardant, an antioxidant, a filler (silica, glass powder, ceramicpowder, metal powder and so on), a resin for modification and so on, solong as the advantages of the present invention are not worsenedthereby.

According to a production method of the invention which comprises usingthe above-described actinic radiation-curable resin composition,irradiating a molding surface of the actinic radiation-curable resincomposition with an actinic radiation to form a cured resin layer havinga shape pattern, then providing the actinic radiation-curable resincomposition for one layer on the above-described cured resin layer toform a molding surface, irradiating the molding surface with the actinicradiation to form a cured resin layer having a shape pattern, andrepeating this fabricating procedure, a three-dimensional objectaccording to the present invention wherein at least part of a pluralityof cured resin layers accumulated have a sea-island microstructure isproduced.

Examples of the actinic radiation to be used in the above method includeactinic radiations such as ultraviolet ray, electron beam, X-ray, radialray and high frequency wave. Among them, ultraviolet ray having awavelength of form 300 to 400 nm is preferably employed from theeconomical viewpoint. As the light source therefor, use can be made ofan ultraviolet laser (for example, Ar laser, He—Cd laser or the like), amercury lamp, a xenon lamp, a halogen lamp, a fluorescent lamp and soon. Among them, a laser source is preferably employed, since it canelevate the energy level so as to shorten the fabricating time and,moreover, establishes a high fabricating accuracy owing to its superiorfocusing ability.

According to the production method of the invention as described above,it is possible to intentionally produce, for example:

-   -   a three-dimensional object having a layered structure as shown        in FIG. 1(i), namely, a three-dimensional object wherein island        components b are almost evenly distributed in the sea components        a in all of the cured resin layers (L₁ to L_(m+n)) constituting        the three-dimensional object; or    -   a three-dimensional object having a layered structure as shown        in FIG. 1(ii), namely, a three-dimensional object wherein island        components b are distributed in the sea components a in all of        the cured resin layers (L₁ to L_(m+n)) constituting the        three-dimensional object but, in each cured resin layer, the        island components b do not exist in the upper portion (the        part c) located in the actinic radiation-irradiated surface but        are unevenly dispersed in the lower portion thereof.

The three-dimensional object as shown in FIG. 1(i) may be obtained byappropriately altering the composition by, for example, optionallylowering the molecular weight of the polyalkylene ether compound asdescribed above, increasing the content of the oxetane compound, orelevating the concentration of the cationic polymerization initiator.

The three-dimensional object as shown in FIG. 1(ii) may be obtained byappropriately altering the composition by, for example, optionallyelevating the molecular weight of the polyalkylene ether compound asdescribed above, using a branched polyalkylene ether compound,decreasing the content of the oxetane compound or lowering theconcentration of the cationic polymerization initiator.

Since these methods of intentionally forming three-dimensional objectsare affected by the properties of a number of materials to be used inthe production of the three-dimensional objects, they are not restrictedto the above procedures.

A three-dimensional object according to the present invention is notrestricted in the overall shape, dimension, intended use and so onthereof. Typical examples of use of a three-dimensional object accordingto the present invention include products for practical use such as amodel for examining the appearance mode in the course of design, a modelfor checking the function of a part, a matrix die for structuring atemplate, a base model for structuring a die, a part having acomplicated microstructure, a three-dimensional part having acomplicated structure and so on, though the present invention is notrestricted thereto. The three-dimensional object according to thepresent invention is particularly suitable for products for practicaluse such as a model of a delicate part with a need for a high impactresistance, a part having a complicated microstructure and athree-dimensional part having a complicated structure. More specificallyspeaking, it is usable as models of delicate parts, electric andelectronic parts, furniture, architectural structures, automobile parts,various containers, template and so on, matrices, processing members andparts thereof for practical use in some cases.

To effectively use the three-dimensional object according to the presentinvention in the uses as described above without suffering fromdeformation due to heat or the like, it is preferred that thethree-dimensional object according to the present invention has a heatdeformation temperature determined by the method as will be described inthe following EXAMPLES of 45° C. or higher, still preferably 48° C. orhigher.

EXAMPLES

Now, the present invention will be described in greater detail byreference to the following EXAMPLES. However, it is to be understoodthat the invention is not restricted to these EXAMPLES. In theseEXAMPLES, all “parts” means parts by mass.

In the following EXAMPLES, the viscosity of a photo curable resincomposition was measured by putting the photo curable resin compositioninto a thermostat at 25° C., adjusting the liquid temperature to 25° C.and measuring the viscosity by using a B type viscometer (manufacturedby Tokyo Keiki Co., Ltd.).

Further, the tensile strength, tensile elongation, tensile modulus,flexural strength and flexural modulus of a three-dimensional object (atest piece) obtained in the following EXAMPLES were measured inaccordance with JIS K7113.

Furthermore, the impact strength and heat deformation temperature of athree-dimensional object (a test piece) obtained in the followingEXAMPLES were measured by the following methods.

(Impact Strength)

Notched Izod impact strength was measured in accordance with JIS K7110.

(Heat Deformation Temperature)

Heat deformation temperature was measured by the method A (load on testpiece=1.813 MPa) in accordance with JIS K7207.

Example 1

(1) 1,800 parts of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 500 parts of 2,2-bis(4-(acryloxydiethoxy)phenyl)propane(“NK ESTER A-BPE-4” manufactured by Shin-Nakamura Chemical Co., Ltd.:having 4 mol of ethylene oxide unit added), 300 parts of propyleneoxide-denatured pentaerythritol tetraacrylate (“ATM-4P” manufactured byShin-Nakamura Chemical Co., Ltd.), 300 parts of3-methyl-3-hydroxymethyloxetane and 300 parts of polytetramethyleneglycol (number-average molecular weight 2,000, glass transitiontemperature −70° C.) were mixed together and stirred at 20 to 25° C. forabout 1 hour to prepare a mixture (total mass of the mixture 3,200parts).

(2) To the mixture obtained in the above (1), 60 parts of1-hydroxy-cyclohexyl phenyl ketone (“Irgacure 184” manufactured by CibaSpecialty Chemicals) as a photo radical polymerization initiator, and 90parts of “UVI-6974” manufactured by Dow Chemical Japan (prepared bydissolving 50 parts of a photo cationic polymerization initiator mixturecontaining bis(4-(diphenylsulfonio)phenyl)sulfide hexafluoroantimonateand (4-phenylthiophenyl)diphenylsulfonium hexafluoroantimonate at a massratio of 2:1 in 50 parts of propylene carbonate (solvent)) as a photocationic polymerization initiator were added under blocking ultravioletlight. The resultant mixture was mixed while stirring at a temperatureof 25° C. for about 1 hour until the components were completelydissolved to thereby give a photo curable resin composition (an actinicradiation-curable resin composition). When measured at 25° C., theviscosity of this photo curable resin composition was 368 mPa·s.

(3) By using the photo curable resin composition obtained in the above(2), a dumbbell-shaped test piece (a three-dimensional object) inaccordance with JIS K7113 was produced by stereolithography with the useof an ultrahigh optically molding system (“SOLIFORM 500C” manufacturedby Teijin Seiki) upon irradiation with a semiconductor laser (power 175mW, wavelength 355 nm) at an irradiation energy of 20 to 30 mJ/cm², aslice pitch (layer thickness) of 0.1 mm and an average fabricating timeper layer of 2 minutes.

(4) When the test piece obtained in the above (3) was observed with thenaked eye, it was a well-fabricated object (a three-dimensional object)without any deviation. Then the tensile strength, tensile elongation,tensile modulus, flexural strength, flexural modulus, impact strengthand heat deformation temperature of the test piece obtained in the above(3) were measured by the methods as described above. Table 1 shows theresults.

(5) Then, the test piece obtained in the above (3) was sliced in thelongitudinal direction (thickness direction) with a microtome(“REICBRERT URTRACUT S” manufactured by LEICA) in a thickness of 50 mm.After staining with a 0.5% aqueous ruthenium tetraoxide (RuO₄) solutionat room temperature (25° C.) for 10 minutes, the slice was observed andphotographed by using a transmission electron microscope (“LEM-2000”manufactured by Topcon) under an accelerating voltage of 100 KV. As FIG.2 (a drawing of a photograph) (35000× magnification) shows, a curedresin layer constituting the fabricated object (three-dimensionalobject) had a sea-island microstructure wherein island components beingmade of polyalkylene glycol and having a particle diameter of 20 to 50nm were dispersed in the sea component made of the cured resin. As thedrawing of the photograph of FIG. 2 shows, the island components did notexist in the upper portion of the layer (the photo irradiation surface)but were distributed in the lower portion in each cured resin layer. Thethickness of the island component-free upper portion corresponded to4.5% of the thickness of a single cured resin layer.

Example 2

(1) The procedures of (1) and (2) of EXAMPLE 1 were followed exceptthat, in the procedure (1) of EXAMPLE1,3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate content ischanged into 1600 parts, the mixture amount of3-methyl-3-hydroxymethyloxetane is changed into 400 parts, and themixture amount of polytetramethylene glycol (number-average molecularweight 2,000, glass transition temperature −70° C.), to thereby give aphoto curable resin composition (an actinic radiation-curable resincomposition). When measured at 25° C., the viscosity of this photocurable resin composition was 378 mPa·s.

(2) By using the photo curable resin composition obtained in the above(1), a dumbbell-shaped test piece (a three-dimensional object) inaccordance with JIS K7113 was produced as in the procedure (3) ofEXAMPLE 1.

(3) When the test piece obtained in the above (2) was observed with thenaked eye, it was a well-fabricated object (a three-dimensional object)without any deviation.

Then the tensile strength, tensile elongation, tensile modulus, flexuralstrength, flexural modulus, impact strength and heat deformationtemperature of the test piece obtained in the above (2) were measured bythe methods as described above. Table 1 shows the results.

(4) Then, the test piece obtained in the above (2) was sliced in thelongitudinal direction (thickness direction) with a microtome in athickness of 50 nm as in the procedure (5) of EXAMPLE 1. After stainingwith ruthenium tetraoxide as in the procedure (5) of EXAMPLE 1, theslice was observed and photographed by using a transmission electronmicroscope under an accelerating voltage of 100 KV. Similar to FIG. 2 (adrawing of a photograph), a sea-island microstructure wherein islandcomponents being made of polyalkylene glycol and having a particlediameter of 20 to 50 nm were dispersed in the sea component made of thecured resin was observed. In each cured resin layer, the islandcomponents did not exist in the upper portion of the layer (the photoirradiation surface) but were distributed in the lower portion. Thethickness of the island component-free upper portion corresponded to 4%of the thickness of a single cured resin layer.

Example 3

(1) The procedures of (1) and (2) of EXAMPLE 1 were followed exceptthat, in the procedure (1) of EXAMPLE 2, 400 parts of polyether “PTG-L”manufactured by HODOGAYA CHEMICAL Co., Ltd.) (polyether comprising anoxytetramethylene unit represented by the formula: —CH₂CH₂CH₂CH₂O— and aside chain-containing oxytetramethylene unit having a branched structurerepresented by the formula: —CH₂CH₂CH(CH₃)CH₂O— bonded together atrandom, number-average molecular weight 4,000, glass transitiontemperature −80° C.) are substituted for polytetramethylene glycol(number-average molecular weight 2,000), to thereby give a photo curableresin composition (an actinic radiation-curable resin composition). Whenmeasured at 25° C., the viscosity of this photo curable resincomposition was 568 mPa·s.

(2) By using the photo curable resin composition obtained in the above(1), a dumbbell-shaped test piece (a three-dimensional object) inaccordance with JIS K7113 was produced as in the procedure (3) ofEXAMPLE 1.

(3) When the test piece obtained in the above (2) was observed with thenaked eye, it was a well-fabricated object (a three-dimensional object)without any deviation.

Then the tensile strength, tensile elongation, tensile modulus, flexuralstrength, flexural modulus, impact strength and heat deformationtemperature of the test piece obtained in the above (2) were measured bythe methods as described above. Table 1 shows the results.

(4) Then, the test piece obtained in the above (2) was sliced in thelongitudinal direction (thickness direction) with a microtome in athickness of 50 nm as in the procedure (5) of EXAMPLE 1. After stainingwith ruthenium tetraoxide as in the procedure (5) of EXAMPLE 1, theslice was observed and photographed by using a transmission electronmicroscope under an accelerating voltage of 100 KV. As a result, asea-island microstructure wherein island components being made of theabove-described polyether “PTG-L” and having a particle diameter of 50to 100 nm were dispersed in the sea component made of the cured resinwas observed. In each cured resin layer, the island components did notexist in the upper portion of the layer (the photo irradiation surface)but were distributed in the lower portion. The thickness of the islandcomponent-free upper portion corresponded to 5% of the thickness of asingle cured resin layer.

Comparative Example 1

(1) The procedures of (1) and (2) of EXAMPLE 1 were followed but usingno polytetramethylene glycol to thereby give a photo curable resincomposition (an actinic radiation-curable resin composition). Whenmeasured at 25° C., the viscosity of this photo curable resincomposition was 284 mPa·s.

(2) By using the photo curable resin composition obtained in the above(1), a dumbbell-shaped test piece (a three-dimensional object) inaccordance with JIS K7113 was produced as in the procedure (3) ofEXAMPLE 1.

(3) When the test piece obtained in the above (2) was observed with thenaked eye, it was a well-fabricated object (a three-dimensional object)without any deviation.

Then the tensile strength, ensile elongation, tensile modulus, flexuralstrength, flexural modulus, impact strength and heat deformationtemperature of the test piece obtained in the above (2) were measured bythe methods as described above. Table 1 shows the results.

(4) Then, the test piece obtained in the above (2) was sliced in thelongitudinal direction (thickness direction) with a microtome in athickness of 50 nm as in the procedure (5) of EXAMPLE 1. After stainingwith ruthenium tetraoxide as in the procedure (5) of EXAMPLE 1, theslice was observed and photographed by using a transmission electronmicroscope under an accelerating voltage of 100 KV. As FIG. 3 (a drawingof a photograph) (35000× magnification) shows, a cured resin layerconstituting the fabricated object (three-dimensional object) compriseda homogeneously cured resin having no island component. TABLE 1 Compar-Exam- Exam- Exam- ative ple 1 ple 2 ple 3 Example 1 Polymer for islandsType¹⁾ A A B — Content (mass %)²⁾ 9.8 11.8 11.8 0 Mechanical propertiesTensile strength (MPa) 45 49 36 60 Tensile modulus (MPa) 1700 1700 13002000 Tensile elongation (%) 11.9 15.9 16.9 6.0 Flexural strength (MPa)65 62 53 70 Flexural modulus (MPa) 1980 2000 1700 2500 Impact resistance(J/m) 50 60 65 25 (Notched Izod) Heat deformation 50 47 50 57 temp.(°C.) Color tone of three- Cloudy Cloudy Cloudy Pale yellow dimensionalstructure & trans- parent Appearance of three- Good Good Good Gooddimensional structure Section of three- — — dimensional structurePresence of islands Yes Yes Yes No Particle diameter 20 to 50 20 to 5050 to 100 — of islands¹⁾Type of polymer for islandsA: polytetramethylene glycol (number-average molecular weight 2000)B: polyether “PTG-L” manufactured by HODOGAYA CHEMICAL Co., Ltd.)(polyether copolymer comprising an oxytetramethylene unit and a sidechain-containing oxytetramethylene unit bonded together at random, theside chain-containing oxytetramethylene unit having a branched structurerepresented by the formula: —CH₂CH₂CH(CH₃)CH₂O—)²⁾Content (% by mass) based on the mass of the photo curable resincomposition.

As the above Table 1 shows, the three-dimensional objects (objects bestereolithography) obtained in EXAMPLES 1 to 3 have cured resin layersbeing made of the actinic radiation-curable resin composition and havinga sea-island microstructure wherein fine island components which aremade of a polymer (a polyalkylene ether compound) differing from a curedresin constituting the sea component and have a particle diameter of 20to 2,000 nm are dispersed in the sea component made of the curedpolymer. Owing to this sea-island microstructure, thesethree-dimensional objects have largely improved impact strength comparedwith the three-dimensional object (object by stereolithography) havingno such sea-island microstructure obtained in COMPARATIVE EXAMPLE 1, aswell as other physical properties such as tensile strength comparablethereto.

While the present invention has been described above in detail byreferring specific embodiments thereof, it is obvious for those skilledin the art that various changes and modifications can be made withoutdeparting from the spirit and scope of the invention.

The present application is based on Japanese Patent Application filed onJun. 24, 2003 (Japanese Patent Application 2003-179034), the contents ofwhich is incorporated by reference.

INDUSTRIAL APPLICABILITY

The three-dimensional object according to the present invention is notrestricted in the overall shape, dimension, intended use and so onthereof. Typical examples of use of the three-dimensional objectaccording to the present invention include products for practical usesuch as a model for examining the appearance mode in the course ofdesign, a model for checking the function of a part, a matrix die forstructuring a template, a base model for structuring a metallic die, apart having a complicated microstructure, a three-dimensional parthaving a complicated structure and so on, though the present inventionis not restricted thereto. The three-dimensional object according to thepresent invention is particularly suitable for products for practicaluse such as a model of a delicate part with a need for a high impactresistance, a part having a complicated microstructure and athree-dimensional part having a complicated structure. More specificallyspeaking, it is effectively usable as, for example, models of delicateparts, electric and electronic parts, furniture, architecturalstructures, automobile parts, various containers, template and so on,matrices, processing members and parts thereof for practical use in somecases.

1. A three-dimensional object comprising a plurality of cured resinlayers accumulated to each other, each of the cured resin layers havinga shaped pattern formed by irradiating a molding surface of an actinicradiation-curable resin composition with an actinic radiation, whereinthe three-dimensional object comprises at least cured resin layercomprising a sea-island microstructure in which island components aredispersed in a sea component comprising a cured polymer, the islandcomponents comprise a polymer differing from the cured resinconstituting the sea component, and the island components are fineisland components having a particle diameter of 20 to 2,000 nm.
 2. Thethree-dimensional object as claimed in claim 1, wherein all of theplurality of cured resin layers constituting the three-dimensionalobject have the sea-island microstructure in which island components aredispersed in a sea component comprising a cured polymer, the islandcomponents comprise a polymer differing from the cured resinconstituting the sea component, and the island components are fineisland components having a particle diameter of 20 to 2,000 nm.
 3. Thethree-dimensional object as claimed in claim 1, wherein each of thecured resin layers constituting the three-dimensional object has athickness of 10 to 500 μm.
 4. The three-dimensional object as claimed inclaim 1, wherein, in each of the cured resin layers having thesea-island microstructure, the island components do not exist in anupper portion of the each of the cured resin layers, the upper portionbeing located in an actinic radiation-irradiated surface of the each ofthe cured resin layers, and the island components exist in a portionfrom the bottom part of the each of the cured resin layers to an upwardpart along the thickness of the each of the cured resin layers.
 5. Thethree-dimensional object as claimed in claim 4, wherein the upperportion containing no island component has a thickness of 2 to 10% withrespect to the thickness of the each of the cured resin layers.
 6. Thethree-dimensional object as claimed in claim 1, wherein each of thecured resin layers having the sea-island microstructure has a sum of theisland components of 1 to 30% by mass with respect to the mass of theeach of the cured resin layers.
 7. The three-dimensional object asclaimed in claim 1, wherein the polymer constituting the islandcomponents has a glass transition temperature of lower than 40° C. 8.The three-dimensional object as claimed in claim 1, wherein the polymerconstituting the island components is a polyalkylene ether compoundhaving a number average molecular weight of 500 to 10,000.
 9. Thethree-dimensional object as claimed in claim 1, wherein the seacomponent comprises the cured resin formed by using at least one actinicradiation-polymerizable compound selected from the group consisting of acationic-polymerizable organic compound capable of undergoing cationicpolymerization upon irradiation with an actinic radiation and aradical-polymerizable organic compound capable of undergoing radicalpolymerization upon irradiation with an actinic radiation.
 10. Thethree-dimensional object as claimed in claim 1, wherein the seacomponent comprises the cured resin formed by using both of acation-polymerizable organic compound and a radical-polymerizableorganic compound.
 11. The three-dimensional object as claimed in claim9, wherein the cation-polymerizable organic compound is a compoundhaving an epoxy group, and the radical-polymerizable organic compound isa compound having a (meth)acryl group.
 12. A method of producing athree-dimensional object having a sea-island microstructure as claimedin claim 1, which comprises: irradiating a molding surface of an actinicradiation-curable resin composition with an actinic radiation to form acured resin layer having a shape pattern; and repeating a fabricatingprocedure comprising: providing an actinic radiation-curable resincomposition for one layer on a cured resin layer to form a moldingsurface; and irradiating the molding surface with an actinic radiationto form a cured resin layer having a shape pattern, so as to produce thethree-dimensional object comprising a plurality of cured resin layersaccumulated, wherein the fabricating procedure is performed by using anactinic radiation-curable resin composition comprising a homogeneousmixture of actinic radiation-curable resin component with a component tobecome polymeric island components having a particle diameter of 20 to2,000 nm upon irradiation, and the actinic radiation-curable resincomponent is capable of forming a cured resin as a sea component uponthe irradiation.
 13. The method as claimed in claim 12, wherein theactinic radiation-curable resin composition comprises: at least oneactinic radiation-polymerizable compound as the cured resin of the seacomponent, the at lease one active ray-polymerizable compound beingselected from the group consisting of a cationic-polymerizable organiccompound capable of undergoing cationic polymerization upon irradiationwith an actinic radiation and a radical-polymerizable organic compoundcapable of undergoing radical polymerization upon irradiation with anactinic radiation; and a polyalkylene ether compound of 500 to 10,000 asthe polymer to become the polymeric island components.
 14. The method asclaimed in claim 12, wherein the cationic-polymerizable organic compoundis a compound having an epoxy group, and the radical-polymerizableorganic compound is a compound having a (meth)acryl group.
 15. Themethod as claimed in claim 12, wherein a content of the polymer tobecome the polymeric island components is from 1 to 30% by mass withrespect to the mass of the actinic radiation-curable resin compositionused for forming the cured resin layer having the sea-islandmicrostructure.
 16. The method as claimed in claim 12, wherein theactinic radiation-curable resin composition comprises an oxetanecompound together with a cationic-polymerizable organic compound havingan epoxy group.